Respiratory Rate Measured by Pressure Variation During HFNC

Monitoring the respiratory rate is important during procedural sedation. Several methods of measuring the respiratory rate are available, but most are unreliable and the most reliable method (capnography) is not available during the use of High Flow Nasal Cannula (HFNC) oxygen. We hypothesize that measuring the pressure variation in the HFNC-circuit is a reliable method of measuring the respiratory rate. An experimental study, using healthy volunteers that will breath in three guided respiratory rates, compares the measurements of respiratory rate by the pressure variation in the HFNC circuit with measurements of respiratory rate by an ECG-derived method and a manual count by an physician. A secondary outcome will be the ability to measure the size of pressure difference, in order to determine its feasiblity to use it as a surrogate for tidal volume or respiratory effort.